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node-feature-discovery/source/kernel/kernel.go
Markus Lehtonen a2b9df5cd3 nfd-worker: rework configuration handling
Extend the FeatureSource interface with new methods for configuration
handling. This enables easier on-the fly reconfiguration of the
feature sources. Further, it simplifies adding config support to feature
sources in the future. Stub methods are added to sources that do not
currently have any configurability.

The patch fixes some (corner) cases with the overrides (--options)
handling, too:
- Overrides were not applied if config file was missing or its parsing
  failed
- Overrides for a certain source did not have effect if an empty config
  for the source was specified in the config file. This was caused by
  the first pass of parsing (config file) setting a nil pointer to the
  source-specific config, effectively detaching it from the main config.
  The second pass would then create a new instance of the source
  specific config, but, this was not visible in the feature source, of
  course.
2020-05-21 00:59:37 +03:00

218 lines
5 KiB
Go

/*
Copyright 2018 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package kernel
import (
"bytes"
"compress/gzip"
"io/ioutil"
"log"
"os"
"regexp"
"strings"
"k8s.io/apimachinery/pkg/util/validation"
"sigs.k8s.io/node-feature-discovery/source"
)
// Configuration file options
type Config struct {
KconfigFile string
ConfigOpts []string `json:"configOpts,omitempty"`
}
// newDefaultConfig returns a new config with pre-populated defaults
func newDefaultConfig() *Config {
return &Config{
KconfigFile: "",
ConfigOpts: []string{
"NO_HZ",
"NO_HZ_IDLE",
"NO_HZ_FULL",
"PREEMPT",
},
}
}
// Implement FeatureSource interface
type Source struct {
config *Config
}
func (s *Source) Name() string { return "kernel" }
// NewConfig method of the FeatureSource interface
func (s *Source) NewConfig() source.Config { return newDefaultConfig() }
// GetConfig method of the FeatureSource interface
func (s *Source) GetConfig() source.Config { return s.config }
// SetConfig method of the FeatureSource interface
func (s *Source) SetConfig(conf source.Config) {
switch v := conf.(type) {
case *Config:
s.config = v
default:
log.Printf("PANIC: invalid config type: %T", conf)
}
}
func (s *Source) Discover() (source.Features, error) {
features := source.Features{}
// Read kernel version
version, err := parseVersion()
if err != nil {
log.Printf("ERROR: Failed to get kernel version: %s", err)
} else {
for key := range version {
features["version."+key] = version[key]
}
}
// Read kconfig
kconfig, err := s.parseKconfig()
if err != nil {
log.Printf("ERROR: Failed to read kconfig: %s", err)
}
// Check flags
for _, opt := range s.config.ConfigOpts {
if val, ok := kconfig[opt]; ok {
features["config."+opt] = val
}
}
selinux, err := SelinuxEnabled()
if err != nil {
log.Print(err)
} else if selinux {
features["selinux.enabled"] = true
}
return features, nil
}
// Read and parse kernel version
func parseVersion() (map[string]string, error) {
version := map[string]string{}
// Open file for reading
raw, err := ioutil.ReadFile("/proc/sys/kernel/osrelease")
if err != nil {
return nil, err
}
full := strings.TrimSpace(string(raw))
// Replace forbidden symbols
fullRegex := regexp.MustCompile("[^-A-Za-z0-9_.]")
full = fullRegex.ReplaceAllString(full, "_")
version["full"] = full
// Regexp for parsing version components
re := regexp.MustCompile(`^(?P<major>\d+)(\.(?P<minor>\d+))?(\.(?P<revision>\d+))?(-.*)?$`)
if m := re.FindStringSubmatch(full); m != nil {
for i, name := range re.SubexpNames() {
if i != 0 && name != "" {
version[name] = m[i]
}
}
}
return version, nil
}
// Read gzipped kernel config
func readKconfigGzip(filename string) ([]byte, error) {
// Open file for reading
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
// Uncompress data
r, err := gzip.NewReader(f)
if err != nil {
return nil, err
}
defer r.Close()
return ioutil.ReadAll(r)
}
// Read kconfig into a map
func (s *Source) parseKconfig() (map[string]string, error) {
kconfig := map[string]string{}
raw := []byte(nil)
var err error
// First, try kconfig specified in the config file
if len(s.config.KconfigFile) > 0 {
raw, err = ioutil.ReadFile(s.config.KconfigFile)
if err != nil {
log.Printf("ERROR: Failed to read kernel config from %s: %s", s.config.KconfigFile, err)
}
}
// Then, try to read from /proc
if raw == nil {
raw, err = readKconfigGzip("/proc/config.gz")
if err != nil {
log.Printf("Failed to read /proc/config.gz: %s", err)
}
}
// Last, try to read from /boot/
if raw == nil {
// Get kernel version
unameRaw, err := ioutil.ReadFile("/proc/sys/kernel/osrelease")
uname := strings.TrimSpace(string(unameRaw))
if err != nil {
return nil, err
}
// Read kconfig
raw, err = ioutil.ReadFile(source.BootDir.Path("config-" + uname))
if err != nil {
return nil, err
}
}
// Regexp for matching kconfig flags
re := regexp.MustCompile(`^CONFIG_(?P<flag>\w+)=(?P<value>.+)`)
// Process data, line-by-line
lines := bytes.Split(raw, []byte("\n"))
for _, line := range lines {
if m := re.FindStringSubmatch(string(line)); m != nil {
if m[2] == "y" || m[2] == "m" {
kconfig[m[1]] = "true"
} else {
value := strings.Trim(m[2], `"`)
if len(value) > validation.LabelValueMaxLength {
log.Printf("WARNING: ignoring kconfig option '%s': value exceeds max length of %d characters", m[1], validation.LabelValueMaxLength)
continue
}
kconfig[m[1]] = value
}
}
}
return kconfig, nil
}